THE SECONDARY STRUCTURE OF BACTERIORHODOPSIN IN ORGANIC SOLUTION - A FOURIER-TRANSFORM INFRARED STUDY

Fourier transform infrared spectroscopy is used to estimate the secondary structure of bacteriorhodopsin dissolved in chloroform-methanol (1:1 v/v), 0.1 M LiClO4. Curve-fitting of the deconvolved spectra in the amide I region shows that the total content of alpha-helices, reverse turns and beta-sheets are similar to the native state. However, the alpha(II)-helices, which are the major helical class in native bacteriorhodopsin, are greatly decreased in the solubilized sample. Similarly, the reverse turns and the beta-sheets are strongly altered.